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Antimalarial effects of peptide inhibitors of a Plasmodium falciparum cysteine proteinase.

We previously identified a Plasmodium falciparum trophozoite cysteine proteinase (TCP) and hypothesized that it is required for the degradation of host hemoglobin by intraerythrocytic malaria parasites. To test this hypothesis and to evaluate TCP as a chemotherapeutic target, we examined the antimalarial effects of a panel of peptide fluoromethyl ketone proteinase inhibitors. For each inhibitor, effectiveness at inhibiting the activity of TCP correlated with effectiveness at both blocking hemoglobin degradation and killing cultured parasites. Benzyloxycarbonyl (Z)-Phe-Arg-CH2F, the most potent inhibitor, inhibited TCP at picomolar concentrations and blocked hemoglobin degradation and killed parasites at nanomolar concentrations. Micromolar concentrations of the inhibitor were nontoxic to cultured mammalian cells. These results support the hypothesis that TCP is a necessary hemoglobinase and suggest that it is a promising chemotherapeutic target.

Animals↗

Possible physico-chemical processes in human dentin caries.

This study correlated ultrastructural observations on the presence of beta-tricalcium phosphate (beta-TCP) in arrested dentin caries with physico-chemical observations on the in vitro formation of Mg-substituted beta-TCP. The ultrastructural studies were made using high-resolution transmission electron microscopy (TEM) with the capability of microdiffraction and microanalysis on sites less than 10 nm in diameter. Mg-substituted beta-TCP was obtained, by a precipitation method, from solutions with Mg/Ca molar ratios of 5/95 and higher. Such correlations led to the postulation of a possible chronological sequence of physico-chemical events occurring at the crystal level during the progress and arrest of caries in human dentin. It is suggested that the initial mechanism for the observed occurrence of large crystals of Mg-substituted beta-TCP and of apatite in the tubule lumen is due to the dissolution of the dentin mineral (a CO3- and Mg-rich calcium OH-apatite) and reprecipitation of Mg-substituted beta-TCP, followed by that of CO3- and Mg-poor apatite.

Calcium Phosphates↗

Pathologic effects of butylated triphenyl phosphate-based hydraulic fluid and tricresyl phosphate on the adrenal gland, ovary, and testis in the Fischer-344 rat.

Triaryl phosphates including tricresyl phosphate (TCP) and butylated triphenyl phosphates (BTPs) are used in the commercial manufacture of plastics, lubricants, and hydraulic fluids. Recent reports implicate these compounds as endocrine and reproductive toxicants in rodents. The objectives of this study were to develop and characterize a rat model to investigate the mechanism(s) of toxicity of triaryl phosphate-based hydraulic fluids and to elucidate potential mechanistic pathways of toxicity through studies of structural/functional relationships. Groups of male and female rats received daily oral doses of either sesame oil alone or 1.7 g/kg of BTP or 0.4 g/kg TCP in sesame oil vehicle or 2.8 g/kg neat BTP for 20, 40, and 60 days. Light microscopic, morphometric, ultrastructural, and histochemical studies revealed hypertrophy and cholesteryl lipidosis of adrenocortical (both sexes) and ovarian interstitial cells that were progressive with duration of exposure. Minimal degeneration was observed in the adrenal cortex and ovary. TCP caused the most severe lesions in both the adrenal gland and ovary, but the morphologic and histochemical changes produced were similar for both compounds, suggesting a common mechanism of toxicity. Decreased testicular weight and degeneration of seminiferous tubules were detected only in TCP-treated rats. The Fischer-344 rat model using TCP and BTP administered by gavage is a valuable system to study mechanisms of endocrine and reproductive toxicity induced by triaryl phosphate-based hydraulic fluids.

Adrenal Cortex↗

Biocompatibility of Beta-tricalcium phosphate root replicas in porcine tooth extraction sockets - a correlative histological, ultrastructural, and x-ray microanalytical pilot study.

This investigation studies porcine tissue response in tooth extraction sockets treated with root replicas made out of Beta-tricalcium phosphate (Beta-TCP; Beta-Ca(3)(PO(4))(2)) granules, molded and held together by thermal fusion of a thin film of polyglycolic-polylactic acid copolymer. Six left mandibular third incisors (n (1)/4 6) of experimental pigs are treated with the root replicas and four contralateral incisors are used as nontreated controls (n (1)/4 4). Two animals each were killed at 20, 40, and 60 weeks of observation periods. The mandibular jaw segments were prepared in toto for light microscopy by resin embedding and serial ground sectioning. Additionally, one Beta-TCP-treated socket at 60 weeks was thoroughly investigated by correlative light, electron microscopic and electron probe X-ray microanalysis to assess the bio-absorbability and host removal of the replica material from the implant site. The extraction wounds of the animals healed satisfactorily with very little histologically observable differences in the healing pattern of the test and control sites. The Beta-TCP was completely removed from extracellular sites, but at 60 weeks, remnants of it were found in the cytoplasm of multinucleated giant cells. The root replicas made out of Beta-TCP were biocompatible and bioabsorbable. Osseous healing occurred both in the test and control sockets, but the healing process was delayed due to the presence of Beta-TCP particles.

Animals↗

Lack of significant association of an insertion/deletion polymorphism in the angiotensin converting enzyme (ACE) gene with tropical calcific pancreatitis.

BACKGROUND: The genetic basis of tropical calcific pancreatitis (TCP) is different and is explained by mutations in the pancreatic secretory trypsin inhibitor (SPINK1) gene. However, mutated SPINK1 does not account for the disease in all the patients, neither does it explain the phenotypic heterogeneity between TCP and fibro-calculous pancreatic diabetes (FCPD). Recent studies suggest a crucial role for pancreatic renin-angiotensin system during chronic hypoxia in acute pancreatitis and for angiotensin converting enzyme (ACE) inhibitors in reducing pancreatic fibrosis in experimental models. We investigated the association of ACE gene insertion/deletion (I/D) polymorphism in TCP patients using a case-control approach. Since SPINK1 mutations are proposed a modifier role, we also investigated its interaction with the ACE gene variant. METHODS: We analyzed the I/D polymorphism in the ACE gene (g.11417_11704del287) in 171 subjects comprising 91 TCP and 80 FCPD patients and compared the allelic and genotypic frequency in them with 99 healthy ethnically matched control subjects. RESULTS: We found 46% and 21% of TCP patients, 56% and 19.6% of FCPD patients and 54.5% and 19.2% of the healthy controls carrying the I/D and D/D genotypes respectively (P>0.05). No significant difference in the clinical picture was observed between patients with and without the del allele at the ACE in/del polymorphism in both categories. No association was observed with the presence or absence of N34S SPINK1 mutation in these patients. CONCLUSION: We conclude that the ACE insertion/deletion variant does not show any significant association with the pathogenesis, fibrosis and progression of tropical calcific pancreatitis and the fibro-calculous pancreatic diabetes.

Adult↗

Cemented cup stability during lever-out testing after acetabular bone impaction grafting with bone graft substitutes mixes containing morselized cancellous bone and tricalcium phosphate--hydroxyapatite granules.

Bone defects after failed total hip arthroplasty can be reconstructed with impacted morselized bone grafts and a cemented cup. In the near future the amount of bone grafts available for surgical purposes will be insufficient. Ceramic calcium phosphates [tricalcium phosphate (TCP) and hydroxyapatite (HA)] have been widely considered as potential bone graft substitutes or bone graft extenders. In the past, mechanical experiments have been performed to determine implant stability of bone grafts and ceramic TCP-HA granules mixes under a compressive load. However, in-vivo migration studies suggest that shear loading may be equally important. This in-vitro study investigated the initial stability of cups reconstructed with various mixes of bone grafts and ceramic TCP-HA granules in a lever-out situation, where shearing is the predominant loading mode. It was found that the cups reconstructed with mixes of bone graft and TCP-HA granules exhibited greater mechanical stability than the cups reconstructed with bone grafts only. It is concluded that from a mechanical standpoint, when considering shear force resistance, 50-50 per cent volume mix and 25-75 per cent volume mix of morselized cancellous bone graft and TCP-HA granules both provide adequate initial cup stability and can be used for acetabular reconstructions with the bone impaction grafting technique.

Acetabulum↗

Fluoromethylated and hydroxymethylated derivatives of N-methyl-D-aspartate receptor antagonist 1-[1-(2-thienyl)cyclohexyl]piperidine.

Derivatives with fluoromethyl and hydroxymethyl groups on the cyclohexyl ring of 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP), a noncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptor, were tested in a radioligand binding assay to evaluate their ability to inhibit [3H]TCP binding by rat brain homogenates. The potencies of these compounds as antagonists of NMDA and L-glutamate responses were also compared using a rat cortical slice preparation. One of the analogs, cis-2-hydroxymethyl-r-1-(N-piperidyl)-1-(2-thienyl) cyclohexane (5) was found to show a high affinity (IC50 = 16 nM) for the phencyclidine (PCP) binding sites, very close to that of TCP, and to be 38-fold more potent in binding than its trans isomer. Fluoromethyl and hydroxymethyl substitutions at C4 position of the cyclohexyl ring of TCP clearly reduced the affinity by at least one order of magnitude relative to TCP.

Animals↗

Role of brain amines in the fetal hyperpyrexia caused by tranylcypromine in LiCl-pretreated rats.

Tranylcypromine (TCP), a monoamine oxidase inhibitor, caused a fatal hyperpyrexia in rats pretreated with LiCl once a day for 4 days. Pretreatment with LiCl alone did not alter the level of serotonin (5-HT), dopamine (DA) and norepinephrine (NE) in the brain. In fatal hyperpyrexia caused by LiCl plus TCP, the brain 5-HT and DA levels were increased, whereas the brain NE level was decreased. Reserpine and alpha-methyl-p-tyrosine completely prevented the hyperpyrexia, but FLA-63 did not show any effect. The hyperpyrexia was completely prevented by p-chlorophenylalanine (PCPA) given 72 hours before TCP but not by PCPA given 24 hours before TCP. Haloperidol and chlorpromazine, DA receptor blockers, inhibited the fatal hyperpyrexia, while cyproheptadine and methysergide, 5-HT receptor blockers, did not. These results suggest that DA plays an essential role in the hyperpyrexia induced by the combination of TCP and LiCl in rats, but the involvement of 5-HT is inconclusive.

Amines↗

Evaluation of pluronic polyols as carriers for grafting materials: study in rat calvaria defects.

BACKGROUND: Pluronic polyols are a family of non-ionic surfactants currently used as drug carriers for antibiotic, anti-inflammatory, and anti-neoplastic agents. Therapeutic administration of non-ionic surface-active agents is known to facilitate early collagen synthesis and microcirculation, thus promoting wound healing. The purpose of this study was to determine the in vivo effects of pluronic polyols combined with either an allograft or an alloplast on the healing of critical-sized calvarial defects. METHODS: One hundred fifty (150) adult (95 to 105 days old) male Sprague-Dawley rats weighing between 375 and 425 g were randomly and evenly assigned to each of 15 separate treatment groups and anesthetized, and 8 mm calvarial critical-sized defects were created. Pluronic F-68 (F-68) or pluronic F-127 (F-127) was administered either topically or systemically and in conjuction with demineralized bone powder (DBP), tricalcium phosphate (TCP), or non-grafted controls. Pluronic polyols are easily mixed with either DBP or TCP to improve handling ease. Calvaria were harvested at 12 weeks postsurgery and evaluated histomorphometrically, by contact radiography with subsequent densitometric analysis, through energy spectrometry utilizing a scanning electron microscope, and by fluorescent microscopy. RESULTS: There was a significant difference in the percentage of bone fill among the control, TCP, and DBP only groups, P <0.05. The only significant difference within any of these groups was between the TCP control and TCP plus systemic F-127, P<0.05. CONCLUSIONS: Although there were isolated differences, the overall trend was that the pluronic polyol and the mode of administration did not result in a significant change in bone wound healing as measured by the percentage of bone fill. Pluronic polyols may be considered as carriers for osseous graft materials.

Absorptiometry, Photon↗

Beta-tricalcium phosphate combined with recombinant human bone morphogenetic protein-2: a substitute for autograft, used for packing interbody fusion cages in the canine lumbar spine.

Beta-tricalcium phosphate (beta-TCP) combined with recombinant human bone morphogenetic protein-2 (BMP-2) was examined as a substitute for autograft for packing into interbody fusion cages in the canine lumbar spine model. Discectomy and interbody cage fusion were performed at three disc spaces in eight dogs. Examination of microradiographs and histological sections of the lumbar spine at 16 weeks postsurgery revealed three fusions in the autograft cages (Group A), three in the beta-TCP cages (Group B), and five in the beta-TCP-BMP-2 cages (Group C). The mean percentage of trabecular bone area in the cages was 51.9% in Group A, 48.8% in Group B, and 65.6% in Group C. Mean percentage of trabecular bone formation and mechanical stiffness were highest in the cages filled with beta-TCP and BMP-2. Combination of BMP to beta-TCP may act as an osteoconductive and osteoinductive bone graft substitute in clinical spine surgery.

Animals↗

[Assessment of beta-tricalcium phosphate as a carrier for bone formation promoting agent, TAK-778-SR].

PURPOSE: The aim of this study was to evaluate the combination of TAK-778-SR which was sustained-release microcapsules of a bone formation stimulant, TAK-778, and its carrier beta-tricalcium phosphate (beta-TCP) blocks (pore rates 60%, 75% respectively). The difference of their abilities in bone-formation was evaluated histomorphologically by varying the following conditions: with or without TAK-778, pore ratio of carrier and embedding period. METHODS: Nine-week-old female SD rats were used. After removing the parietal bone from the head with a trephine bar, the defects were refilled by beta-TCP blocks immersed with or without TAK-778 under the following conditions: saline solution, release microcapsules only, and release microcapsules with TAK-778 (TAK-778-SR). These rats were sacrificed after 5 and 10 weeks and their histological specimens were prepared. Morphological change was observed and the formation rates of each new bone were compared using an NIH imaging program. RESULTS: A significant amount of new bone was morphologically observed in all beta-TCP samples that were treated with TAK-778-SR. A high rate of new bone formation was confirmed in the 10-week samples (pore rate 75%, with TAK-778-SR) with the NIH imaging. CONCLUSIONS: 1. beta-TCP and release microcapsules did not disturb the recovery process. 2. Five- and 10-week samples (pore rate 60%) were absorbed marginally. 3. Absorption was observed in the 5-week samples (pore rate 75%), and it was accelerated further at 10 weeks. 4. An accelerating bone-formation effect of TAK-778-SR was confirmed and beta-TCP block was proved to be highly useful as a carriage material.

Animals↗

Bone formation in beta-tricalcium phosphate-filled bone defects of the rat femur: morphometric analysis and expression of bone related protein mRNA.

The purpose of the current study was to evaluate the bone formation when beta-tricalcium phosphate (TCP) was implanted in bone defects of rat femurs. beta-TCP granules were applied to defects created in the femurs of 65 male rats who were sacrificed 3, 7, 10, 14 or 30 days later. Bone tissues were embedded in paraffin, serial sections were cut and then stained with hematoxylin-eosin. Histomorphometric analyses were also conducted. Furthermore, total mRNAs were extracted, homogenized, and reverse transcribed, after which quantitative PCR assays were conducted with a LightCycler using the double-stranded DNA dye Syber Green I with primers for either rat osteopontin or osteocalcin. Tissues in defects without beta-TCP were used as controls. The amount of newly formed bone tissue in the beta-TCP implanted group was significantly greater in both the side areas and the central area of defects than in the control group. Expressions of osteopontin and osteocalcin mRNAs of cells in the defects of the experimental group were up-regulated compared with the control group at all time periods. Taken together, these results prove that beta-TCP is an appropriate material for osteoconduction and promotes bone formation in bone defects.

Animals↗

Effects of the enamel matrix derivative and beta-tricalcium phosphate on bone augmentation within a titanium cap in rabbit calvarium.

In vitro studies suggest that enamel matrix derivative (EMD) affects the early stages of osteogenic maturation by stimulating bone cell proliferation. In the present study, we evaluated the effects of EMD and beta-tricalcium phosphate (beta-TCP) on bone augmentation within a titanium cap in rabbit calvaria, using 14 adult male Japanese white rabbits. The calvarium was exposed, a circular groove prepared, the marrow penetrated, and a standard hemispherical titanium cap placed in the groove. The cap was filled with a mixture of beta-TCP and EMD at the experimental site, and was filled with beta-TCP alone at the control site. At 1 and 3 months after cap implantation, animals were euthanized, and histological sections prepared. The sections were stained with basic fuchsin and methylene blue, and were examined using light microscopy. At 1 month, EMD tended to increase the amount of bone, but there was no significant difference in the amount of new tissue and mineralized bone between the experimental and control sites. The present findings indicate that the present mixture of EMD and beta-TCP does not accelerate bone formation, compared with beta-TCP alone.

Animals↗

[Tricresyl phosphate residue in garland chrysanthemum and its origin].

Unknown peaks were detected in the chromatogram of garland chrysanthemum extract in analysis of organophosphorus pesticide residues. The unknown peaks were identified as isomers of tricresyl phosphate (TCP) by GC/MS. TCP is used as a plasticizer in polyvinyl chloride, and there is no report of its detection in foods. Therefore, we investigated the origin of TCP detected in garland chrysanthemum. We found no effect of contact with packaging film or polyvinyl chloride sheet used in greenhouses. However, TCP was detected at 0.03 microg/g (average) in 16 of 20 samples of garland chrysanthemum that had been in contact with polyvinyl chloride tubing used for warming greenhouses. These results indicate that TCP migrated to the garland chrysanthemum from the tubing used to keep greenhouses warm.

Agriculture↗

Comparison of carbonate apatite and beta-tricalcium phosphate (resorbable calcium phosphates) implanted subcutaneously into the back of rats.

Bioresorption and biocompatibility of carbonate apatites, both sintered and non-sintered (S-CAP and N-CAP), and of sintered beta-tricalcium phosphate (beta-TCP) were compared by implanting particles of these materials into the back of adult rats. Bioresorption--when evaluated non-destructively with non-decalcified tissues using microfocus X-ray tomography--was essentially the same for N-CAP and beta-TCP, while S-CAP exhibited statistically lower bioresorption at 2, 4, and 12 weeks postoperatively. Biocompatibility--when evaluated by ED1 immunostaining--was in the order of beta-TCP > N-CAP > S-CAP. The intensity of ED1 immunostaining decreased with time, but persisted longer in beta-TCP than in S-CAP and N-CAP, indicating that beta-TCP produced the strongest and most enduring stimulation of macrophages. Although no statistical differences were found in tartrate-resistant acid phosphatase (TRAP) staining among the materials at each implantation period, the degree of TRAP staining for S-CAP was statistically greater at 12 weeks than at 2 and 4 weeks, indicating that osteoclast-like cells were in part responsible for the resorption of the carbonate apatite.

Absorbable Implants↗

[The practical theory of occupational health planning: Part Two--The theoretical background from the priority setting procedure to the post project appraisal making procedure (OPST research report 3)].

This report focuses on the final six procedures of the 8-stage OPSS. The first two procedures were covered in an earlier report. This paper examines the theoretical underpinnings of these six procedures. In the Priority Setting procedure, three factors are compared (TCP; Time/timing, cost, and population) for the OPSS in the general community, and also those in industry. These sometimes differ, especially with respect to responsibility and implementation. TCP allows the appropriate factors to be considered for a more objective prioritization of the various factors. As discussed earlier, the first TCP is used for prioritizing occupational health problems through the Needs assessment procedure. The second TCP prioritizes the countermeasures of those problems selected in the first TCP. In the Program Design procedure, we discuss the MIO (Merit, Impact, Outcome). Merit is defined as the effectiveness of a program as viewed by the company, taking into account the managerial and social merits. Impact refers to the behavioral effectiveness and behavioral change from the viewpoint of the program designer. Outcome refers to the effectiveness of the program from the traditional medical and epidemiological view-point. The study goes on to discuss the relationship amongst participation level, program development, and the subject's compliance, as a means to ensure that subjects participate indirectly through both steps of OHQ. In the Presentation procedure, we summarize the flow of effective presentations in the company setting. This covers initial understanding of the target audience wants, together with what the planner wants to focus on. In this way common issues and themes can be developed. Further assistance is given with strategy formation, presentation aids, time category presentations, evaluation and feedback. In the Process and Final Evaluation procedures, we discuss the objectives, and their significance to the overall process. In the Post Project Appraisal Making procedures, the previous three procedures are strongly affected by each proceeding procedure. In OPSS, we did not include the program development step in the Program Design procedure because the development skills can be referred from behavioral sciences methodologies. In the final part of this paper, we discuss the merits of the underlying theories of behavioral sciences, which have potential to apply to the occupational health settings.

Health Planning↗

Thermal decomposition and reconstruction of hydroxyapatite in air atmosphere.

In this paper, the decomposition and reconstruction behavior of hydroxyapatite (HAP) during heating and cooling in air atmosphere were studied. The commercial HAP were chosen and gradually heated to 1500 degrees C and cooled to room temperature by a program controlled SiC heated furnace. X-ray diffractometer (XRD) and Fourier-transformed infrared (FTIR) analysis were used to investigate the change of crystalline phases and functional groups of HAP at different temperatures. Weight change of samples was recorded by thermogravimetric analysis (TGA) during heating and cooling. The results revealed that HAP would gradually release its OH- ions and transform into OHAP in the temperature of 1000-1360 degrees C. Above 1360 degrees C, the OHAP would decompose into TTCP and alpha TCP phase. The OH- stretching bands of HAP could be traced by FTIR even at the temperature of 1350 degrees C which was the eve of HAP decomposition. It reflected that the HAP did not dehydrate completely before decomposed. We speculated that some of OAP might be formed during dehydration and there were a great amount of OHAP still left in the system even up to the temperature of decomposition. In the temperature of 1400-1500 degrees C, there were no significant different in XRD patterns, only TTCP and alpha TCP crystalline phase were observed. When the HAP gradually cooled down from 1500 degrees C, a part of TTCP and alpha TCP would directly reconstruct into oxyapatite (OAP) around 1350 degrees C. OAP existed in the temperature of 1350 to 1300 degrees C during cooling. When the temperature down to 1290 degrees C, a part of TTCP and alpha TCP reconstructed into OHAP by rehydration reaction and OAP were rehydrated into OHAP as well. At 1100 degrees C, the rest of TTCP and alpha TCP would reconstitute into HAP. As the temperature decreased, the OHAP were gradually rehydrated and reconstituted into HAP.

Biocompatible Materials↗

Treatment of intertrochanteric fractures of the femur with L-trapezoid compression plate and its mechanical principles.

OBJECTIVE: To improve the results of the treatment of unstable types of intertrochanteric fractures of the femur (ITFF) by internal fixation. METHODS: A L-trapezoid compression plate system (L-TCP) was designed and compared to the AO/ASIF angle plates of 95 and 130 (L-AP) with mechanical tests. An Evans Type III model was made, the simulation electrical test with loading on single and both legs were done. The results demonstrated that the stability of the L-TCP fixation was significantly greater, and the stress concentration at the upper screw hole was relevantly smaller than that of L-AP. From June 1986 to June 1998, 82 patients of ITFF were treated with L-TCP fixation. The average age was 67.4 years old (26-91). Seventy-four of those fractures were unstable. Fifty-eight patients were treated with open reduction, and 24 cases were treated by closed reduction and limited open (only lateral aspect of upper femur was exposed) fixation with L-TCP under X-ray monitoring. RESULTS: Sixty-six patients were followed up for 6-69 months. Complications, including 3 wound infection, 1 non-union, 3 coxa varus and 2 implant breakage (9 complications of 7 cases), all occurred in the open reduction group. No complication was found in the closed reduction group. CONCLUSIONS: In the treatment of ITFF, the results of closed reduction and limited open fixation with L-TCP is significantly better than that of open reduction and fully exposed fixation.

Journal Article↗